DavidWms: if you do the test in TR – using workout creator or one of the already-created workouts – then go into the results and select the time period that begins when you start the 95% and ends when you drop off the perch. Selecting this interval will provide you with all the statistics for that section, including average power, which is KM’s estimate of FTP.
If you use this method, you don’t have to go to the end of any particular interval that you have defined.
You can do the test on the road [best slightly uphill or flat] or on the trainer. But you cannot export a custom workout to wahoo/garmin.